Nijkamp’s profile on Google Scholar is polluted. It counts 28,860 citations, but includes papers written by others, like Zoltan Acs and Nobel-prize winner Daniel Kahneman. A Web of Knowledge author search yielded 3,638 citations of his 426 (co-authored) publications, 3,310 excluding self-citations. That’s 7.8 citations per article. His H-index is 29. Typically Nijkamp appears as a co-author on publications. He is the single author of only one of his top 10 most cited articles, ranking 10th, with 58 citations.

January 15, 2014 update: Nijkamp responded in a letter posted here that there may have been some flaws and accidents, but that these are to be expected in what he calls “the beautiful industry of academic publishing”.